The often warring siblings will be forced to put aside their differences -- at least temporarily -- as they embark on a mission to rescue their brother, held captive in Marcel and Davina's hideout. But with years and years of history between Rebekah and Klaus' former protege complicating matters, things may prove a tad more difficult.

"I feel like if he could make [the Rebekah-Marcel relationship] serve him, then he's maybe more in favor of it," Joseph Morgan tells The Hollywood Reporter of Klaus' mindset. "But at the moment it gets him nothing."

In the Oct. 15 episode of The Vampire Diaries spinoff, Klaus discovers key intel about a major player within Marcel's inner circle, putting his plan to unravel Marcel's empire from the inside into motion. Morgan talks to THR about Klaus and Marcel's history, getting Elijah back and teaming up with Rebekah.

We learned quite a bit about Klaus' history with Marcel (Charles Michael Davis), particularly how they first met. What aspects of their backstory most surprised you?

A few things. The way that they met maybe didn't surprise me, just pleased me. I thought that was one of the most wonderful bits of flashback we've ever done, including The Vampire Diaries. Finding him as a young boy and then him living with us -- I thought that was a really wonderful piece of story, the way I rescued him. I suppose the thing that surprised me the most was after that romantic connection between [Marcel] and Rebekah [Claire Holt] when I gave him the choice, he chose not to undagger [Rebekah] so he could become a vampire. That scene, by the way, when Rebekah asked, "What day is it?" after I undagger her, and I say it's been 50 years, Klaus is so devilish in that moment.

Marcel's choice to become a vampire and not undagger Rebekah shined a light on who he was at that time …

It really humanized him well, I thought. The human Marcel was much less guarded, much more open than we've seen vampire Marcel I think.

Why is Klaus so against the Marcel-Rebekah pairing, and do you think he'llevercome around?

First of all Klaus is incredibly possessive over his siblings' love. And you'll see in the future, if either of them spends too much time or affection on someone else, he doesn't like it. He wants to be the center of their world and it really comes from the feeling of not enough affirmation or love as a child -- especially from his parents, his father particularly. He really, really loves Rebekah and no one's ever good enough for her. As for Marcel, that's his friend and the person he brought in as a son. Now that they're starting something special, Klaus feels left out. He's really insecure about that.

I don't know. I feel like if he could make it serve him, then he's maybe more in favor of it. But at the moment it gets him nothing -- other than less attention from his sister and Marcel -- so he doesn't like it.

Now, Rebekah and Klaus are teaming up against Marcel in their attempt to save Elijah (Daniel Gillies). How does that affect their bond?

We saw at the end of the second episode Klaus admitting he gave Elijah to Marcel and that that was a mistake. That was sort of an apology -- or as close to an apology that we're going to get from him. In this moment where we left them last, they're united, and that's a really lovely place for them to be in. That's the unity of family right there. They both want to get their other brother back. I'm not sure how pleased Elijah's going to be with Klaus when he does come back, but that's another story.

Klaus said in the last episode that he always has a plan, so how does he go about getting his brother back?

In episode three you're going to really see Klaus put a plan into effect. The whole episode we're going to see the mechanics of that being put together. We're also going to learn a bit more history about Marcel's relationship with his Nightwalkers.

While Klaus and Rebekah are trying to save Elijah, Marcel and Davina (Danielle Campbell) are figuring out how to kill Originals, but they don't know that Klaus is sired to Marcel. How close do they get to figuring out a way?

One thing we learned from Vampire Diaries that Marcel isn't aware of yet is what happens when you do kill an Original vampire. [Marcel]'s going to be disappointed when he finds out every vampire that Klaus turned dies also. So they're going to have to find a way around that. You'll have to watch to see how close they come to it or whether they manage to do that, but it's certainly an interesting dynamic between her and Marcel. It'll be interesting to see how much power she has and why she has all that power.

If Klaus were to take back the throne from Marcel, what would be his first order of business?

I'm not sure. It's interesting isn't it? What happens after that? The thing about Klaus is he's always going to have enemies because he has this way of making them. So I think he would use that [power] to protect himself. And then his focus, I hope, will move more toward the baby and protecting and raising his child. If he was to take Marcel's place, I'm not sure how loyal those vampires would be to Klaus. Or perhaps he could just redecorate the compound. Change it up a little bit, possibly put in more mirrors knowing Klaus.